1. Field of the Invention
The present invention relates to a water cloud evaluating device for evaluating a water cloud occurring within a lighting chamber for a vehicle lighting fixture.
2. Description of the Related Art
In the related art vehicle lighting fixture, the lighting chamber is typically comprised of a translucent cover and a lamp body. On the rear part of the lamp body, vent holes are often formed to connect the lighting chamber to an outer space of the lighting fixture, thus preventing changes in the atmospheric pressure within the lighting chamber from occurring due to repeated light usage. As a result, a water cloud (i.e., a cloud formed in the lighting chamber due to moisture) is less likely to occur within the lighting chamber.
On the other hand, in this related art vehicle lighting fixture, the water content permeating from the lighting fixture outer space into the lighting chamber through the vent holes forms as condensation (e.g., dew droplets) on an inner surface of a lens to produce a water cloud, unless the structure or arrangement of the vent holes is fully taken into consideration.
Since this related art water cloud is not typically evaluated very precisely by benchmark testing, the water cloud evaluation is made by mounting the lighting fixture on the actual vehicle and driving the vehicle. However, with such an evaluation method, it is necessary to mount the lighting fixture on the actual vehicle. Therefore, it is not easy to perform repeated water cloud evaluation tests, and it is difficult to acquire the precise evaluation results in a short time.
On the contrary, in JP-A-2001-165819, the contents of which is incorporated herein by reference, a water cloud evaluating device was described, comprising a partition member for partitioning a lighting fixture outer space into a front space and a rear space around the outer circumferential portion of a lighting fixture, vehicle outside environment simulation setting means for simulatively setting the front space in a predetermined vehicle outside environment, and vehicle inside environment simulation setting means for simulatively setting the rear space in a predetermined vehicle inside environment.
Employing the water cloud evaluating device as described in the JP-A-2001-165819, precise water cloud evaluation results are acquired by the bench test. However, the following problems arise.
For example, but not by way of limitation, the vehicle lighting fixture is typically varied in shape, dimensions, amount of circulation to the rear side of the lighting fixture, and inclination angle of the translucent cover, depending on the shape of a vehicle body on which the lighting fixture is mounted. Therefore, when the partition member is made from a rigid plate as in the water cloud evaluating device described in the JP-A-2001-165819, it is difficult to appropriate the partition member fabricated for one vehicle lighting fixture to another vehicle lighting fixture. Accordingly, when the water cloud evaluation is made for a new vehicle lighting fixture, it is necessary to fabricate a new partition member in accordance with the shape of the vehicle lighting fixture. Thus, a related art problem results in the water cloud evaluation requiring more time and cost.
Further, in this related art water cloud evaluating device, a water spray unit and an illumination unit are provided as the simulation setting units comprising the vehicle outside simulation setting means, and an air flow generating unit and a temperature/humidity control unit are provided as the simulation setting units comprising the vehicle inside simulation setting means. Since these simulation setting units are stationary, it is not easy to precisely set the front space in a desired vehicle outside environment by simulation, or to precisely set the rear space in a desired vehicle inside environment by simulation.
In this regard, there is yet room for improvement to obtain the water cloud evaluation result a thigh precision. Also, since each simulation setting unit is stationary, there is a related art problem in that it is difficult to perform the operation for installing or removing the vehicle lighting fixture to be evaluated.